BRUSSELS (Reuters) - European Union finance ministers are worried that the European Commission is not applying the bloc's budget rules in the same way to large and small countries, which undermines confidence in the rules, the chairman of euro zone finance ministers said.

Speaking at a hearing in the European Parliament, Jeroen Dijsselbloem, the Dutch finance minister, said the cases of Spain, Portugal and France raised questions about the predictability and objectivity of application of the rules.

"If member states feel that the Commission's decisions are very hard to understand and very hard to predict and are not objective, (that they) are perhaps distinguishing between small member states and large member states, that is a very big worry," Dijsselbloem told parliamentarians.

"I can sense it during the Eurogroup meetings that ministers are becoming a little concerned about this, so I think the Commission really has to understand that the Pact is in their hands, they have to guard it and if people feel that there is a difference in treatment in different situations, between different member states it becomes more and more difficult to ask all of us to comply with what we have agreed," he said.

(Reporting By Jan Strupczewski)